Irwin Unibit step drill bits are ideal for drilling holes in just about any type of thin material. General purpose high speed steel Unibit step drill bits are perfect for use in mild steel, copper, brass, aluminum, plexiglass, wood and laminate. Our titanium nitride coated (TiN) bits resist heat and friction, which extends the life of the cutting edge six times longer than standard step drills. And, our cobalt step drill bits are engineered with m35 cobalt steel for maximum life when drilling in the toughest steel, including stainless steel. Most Unibit step drills are designed with a SpeedPoint tip that guarantees fast starts. They are manufactured with a single flute cutting edge that drills multiple sizes of true, round holes with precise step control. Plus, the hole sizes are permanently laser etched on the inside of the flute, so they can be easily identified throughout the life of the bit.